Method of analysis of alcohol by mass spectrometry

• US 20050070024A1
• Filed: 09/30/2003
• Published: 03/31/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Duc Tien Nguyen, Hoa Duc Nguyen, Trinh Duc Nguyen
• Original Assignee: Duc Tien Nguyen, Hoa Duc Nguyen, Trinh Duc Nguyen
• Inventors: Nguyen, Hoa Duc, Nguyen, Duc Tien, Nguyen, Trinh Duc
• Granted Patent: US 7,439,074 B2
• Time in Patent Office: Days
• US Class Current: 436/131
• CPC Class Codes: G01N 33/60 involving radioactive labelled substances
• CPC Class Codes: G01N 33/98 involving alcohol, e.g. ethanol in breath
• CPC Class Codes: H01J 49/0009 Calibration of the apparatus
• CPC Class Codes: Y10T 436/203332 Hydroxyl containing
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry

Abstract

Method of identification and quantitative analysis of alcohol(s) in a sample by mass spectrometry using stable isotope labeled internal standard is provided. Said internal standard is prepared by reaction of an authentic sample of said alcohol with a stable isotope labeled reagent, and is added to a sample containing said alcohol. Said alcohol in said sample is then quantitatively converted to a chemical compound of identical structure, except the stable isotope atoms, as that of said internal standard using a non-labeled reagent. Said sample is then extracted and the extract is analyzed by mass spectrometry. Identification and quantification of said alcohol are made from a plot of ion ratio of said converted alcohol to said internal standard versus alcohol concentration.

Claims

1. A method of identification and quantification of alcohol(s) in a sample comprising the steps of:

a) combining a known amount of an ester internal standard with said sample comprising said alcohol;

b) contacting said sample with an acid anhydride or an acid chloride to convert said alcohol in said sample into an ester of identical structure as that of said ester internal standard except for the stable isotope atoms;

c) extracting said sample to isolate said ester and said ester internal standard; and

d) analyzing said ester and said ester internal standard by mass spectrometry.

2. The method of claim 1 wherein said mass spectrometric method is the isotope dilution mass spectrometric method using isotope labeled internal standard.

3. The method of claim 1 wherein said alcohol is an alcohol having the following formula R₁OH, R₁CH₂OH, R₁R₂CHOH, R₁R₂R₃COH, wherein R₁, R₂, and R₃ are alkyl, aryl, and heteroatom containing cyclic or non-cyclic groups.

4. The method of claim 1 wherein said ester internal standard is a stable isotope labeled internal standard.

5. The method of claim 1 wherein said ester internal standard is synthesized by reacting an authentic sample of said alcohol with a stable isotope labeled reagent to form said ester internal standard having the following formula R₁OCOR₄ or R₁CH₂OCOR₄ or R₁R₂CHOCOR₄ or R₁R₂R₃OCOR₄ wherein R₄ is a stable isotope labeled alkyl or aryl group.

6. The method of claim 5 wherein said labeled group R₄ is selected from a group consisting of CD₃ CD₂CD₃, and C₆D₅, formed by reacting said alcohol with labeled acid anhydride selected from a group comprising labeled acetic acid anhydride, labeled propionic acid anhydride, and labeled benzoic acid anhydride or labeled acid chloride selected from a group comprising labeled acetyl chloride, labeled propionyl chloride, and labeled benzoyl chloride.

7. The method of claim 1 wherein said extraction step c) can be any appropriate separating methods such as solid phase extraction, liquid-liquid extraction or solid supported liquid-liquid extraction.

8. The method of claim 1 wherein said acid anhydride is selected from a group consisting of acetic acid anhydride, propionic acid anhydride, and benzoic acid anhydride and said acid chloride is selected from a group consisting of acetyl chloride, propionyl chloride, and benzoyl chloride.

9. The method of claim 1 wherein said sample contains either a singularity or a plurality of alcohols.

10. The method of claim 1 wherein said multiple alcohols can be converted to said esters using either a single acid anhydride or a single acid chloride.

11. The method of claim 1 wherein said multiple labeled ester internal standards can be synthesized from said alcohols using either a single labeled acid anhydride or a single labeled acid chloride.

12. The method of claim 1 wherein there is no conversion of said stable isotope labeled ester internal standard to its corresponding non-labeled ester compound during step b).

13. The method of claim 1 wherein said converting step b) is performed in an aqueous environment.

14. The method of claim 1 wherein said converting step b) is performed before said extraction step.

15. The method of claim 1 wherein said converting step b) is quantitative.

16. A method of identification and quantification of alcohol(s) in a sample comprising the steps of:

a) combining a known amount of a carbamate internal standard with said sample comprising said alcohol;

b) contacting said sample with an isocyanate to convert said alcohol in said sample into a carbamate of identical structure as that of said carbamate internal standard except for the stable isotope atoms;

c) extracting said sample to isolate said carbamate and said carbamate internal standard; and

d) analyzing said carbamate and said carbamate internal standard by mass spectrometry.

17. The method of claim 16 wherein said mass spectrometric method is the isotope dilution mass spectrometric method using isotope labeled internal standard.

18. The method of claim 16 wherein said alcohol is an alcohol having the following formula R₁OH, R₁CH₂OH, R₁R₂CHOH, R₁R₂R₃COH, wherein R₁, R₂, and R₃ are alkyl, aryl, and heteroatom containing cyclic or non-cyclic groups.

19. The method of claim 16 wherein said carbamate internal standard is a stable isotope labeled internal standard.

20. The method of claim 16 wherein said carbamate internal standard is synthesized by reacting an authentic sample of said alcohol with a stable isotope labeled reagent to form said carbamate internal standard having the following formula R₁OCONR₄ or R₁CH₂OCONR₄ or R₁R₂CHOCONR₄ or R₁R₂R₃COCONR₄, where R₄ is a stable isotope labeled alkyl or aryl group.

21. The method of claim 20 wherein said labeled group R₄ is selected from a group consisting of CD₃, CD₂CD₃, and C₆D₅, formed by reacting said alcohol with a labeled isocyanate selected from a group comprising labeled methyl isocyanate, labeled ethyl isocyanate, and labeled phenyl isocyanate.

22. The method of claim 16 wherein said extraction step c) can be any appropriate separating methods such as solid phase extraction, liquid-liquid extraction or solid supported liquid-liquid extraction.

23. The method of claim 16 wherein said isocyanate is selected from a group consisting of methyl isocyanate, ethyl isocyanate and phenyl isocyanate.

24. The method of claim 16 wherein said sample contains either a singularity or a plurality of alcohols.

25. The method of claim 16 wherein said multiple alcohols can be converted to said carbamates using a single isocyanate.

26. The method of claim 16 wherein said multiple labeled carbamate internal standards can be synthesized from said alcohols using a single labeled isocyanate.

27. The method of claim 16 wherein there is no conversion of said stable isotope labeled carbamate internal standard to its corresponding non-labeled carbamate compound during said converting step b).

28. The method of claim 16 wherein said converting step b) is performed in an aqueous environment.

29. The method of claim 16 wherein said converting step b) is performed before said extraction step.

30. The method of claim 16 wherein said converting step b) is quantitative.